overflow question

e46er · #1 04-13-2009, 11:43 PM

never ran a herbie but took some physics years ago and it would tell me that a herbie (creating a full syphon with ZERO air) will drain much better than a durso style drain (air takes up space) a 1" durso gives you 600 gph a herbie style drain 1" would not surprise me if it was capable of 900-1000 gph(this was just a guess) i wish i went herbie style so its silent

Canuckgod420 · #2 04-14-2009, 12:37 AM

I guess the best way to know is to do it.
I'm re-doing my entire setup anyways....so good time as any.

sphelps · #3 04-14-2009, 12:57 AM

the main reason a Herbie flows more is head pressure, a standard durso or other standpipe operates at essentially zero head pressure while a Herbie has head pressure equal to the height of the overflow.

Out of curiosity why not share the model number of that pump?

Also when you branch of a line you don't look at it as a single system, for example, ignoring pipe friction, if you have two lines going up 8' you only have 8' of head pressure not 16'. So with your system you haven't analyzed it properly, you have less head pressure than you think.

golf nut · #4 04-14-2009, 01:05 AM

Quote:

Originally Posted by sphelps

if you have two lines going up 8' you only have 8' of head pressure not 16'. So with your system you haven't analyzed it properly, you have less head pressure than you think.

beat me to it, providing it is done properly.

Canuckgod420 · #5 04-14-2009, 01:21 AM

There is no model no on the pump...its an OEM replacement pump for a jetted tub.
The only thing that is on the pump is HP: 1/3. Jetted tub manufacturer, and pump manufacturer(Pentair). I called the tub maker, they in turn gave me the # to the people they talk to about their pumps, and I called them.

Explain your theory on the head pressure please, it would be nice to know for sure.
The way I see it, if I tee off a pump(any pump) the flow coming from either end of the tee would be half of what the flow is straight from the pump...correct?

Canuckgod420 · #6 04-14-2009, 01:28 AM

Yes Myka I know how to calculate head pressure...again, not a rookie....but thanks for that.
I'll detail it for you if that helps you in any way.
My pump would be sitting on the floor of the stand.....approx 3" off the floor, with me so far. Then the pipe turns a 90 then another 90 then runs all the way up the back of the tank, then over the tank into the water....2 more 90's. I guess I should mention that the top off my tank is at eye level.....6 feet up. So actually, I've under calculated my head pressure for just the display alone, each 90 is considered 1 foot of head pressure, so we are looking at 10 feet just for 1 tank. Then theres the prop tank same as above only extra 6 feet to the right.

Canuckgod420 · #7 04-14-2009, 01:31 AM

Oh and on top of all that I am not running 2" pipe back into my tank, at some point I need to reduce the pipes down to 1 or 1.5". So lots more loss right there.

sphelps · #8 04-14-2009, 02:42 AM

Quote:

Originally Posted by Canuckgod420

Yes Myka I know how to calculate head pressure...again, not a rookie....but thanks for that.
I'll detail it for you if that helps you in any way.
My pump would be sitting on the floor of the stand.....approx 3" off the floor, with me so far. Then the pipe turns a 90 then another 90 then runs all the way up the back of the tank, then over the tank into the water....2 more 90's. I guess I should mention that the top off my tank is at eye level.....6 feet up. So actually, I've under calculated my head pressure for just the display alone, each 90 is considered 1 foot of head pressure, so we are looking at 10 feet just for 1 tank. Then theres the prop tank same as above only extra 6 feet to the right.

Easy buddy we're all friends here, but if you want to be a jerk you don't know how to calculate head pressure.

you've got 6 feet of vertical height and I'll assume 1 foot of horizontal. On top of that you've got 4 90s and again I'll also assume a ball valve. Easiest way to calculate head pressure is to use a calculator like the one on RC. Head pressure is also directly related to flow rate so for an example if you run a sequence 2400 (similar to snapper) in your situation (with 1.5" piping) as described you get 6.81 feet of head pressure and 1231gph but if you run a larger pump in the same situation you'll get upwards of 9.8 feet of head pressure. 1 foot per 90 is not accurate.

Unfortunately such an elementary calculator doesn't properly allow for multiple branch calculations however consider this: Yes if you branch the flow to two equal lines you split the flow but your head pressure will decrease. In fact it will decrease for two reasons, lower flow and double the cross sectional area of the pipe. Therefore you can trick such a calculator to give a good estimate. For example, let's assume two pipes from a 2500gph pump, each 1.5" and both have vertical distance of 6 feet and 1 foot horizontal with 4 90s a piece. We can trick the calculator to give us an estimate, remember this is an estimate, you don't want me to do the real thing, trust me

. So use the same pump but we'll assume two 1.5" pipes are pretty close to one 2" pipe (which they are, considering the extra pipe friction from the two 1.5" pipes). We still only have 6 feet of actual head but we'll add the extra 6 feet into the horizontal distance to account for friction loss.
So this is what we got:
Pipe size: 2" (actually two 1.5" lines)
Vertical: 6 feet
Horizontal: 8 feet
90s: 8
Ball valves: 2

Total head pressure: 6.53 feet of head and 1305 gph.

Wow you gained flow, that snapper is looking pretty good, but keep in mind a super rough estimate here, but in such a circumstance you could actually gain "total" flow and reduce head pressure by branching a line to another tank.

Also I thought I'd point out another problem, you seemed to have bought a pump you know nothing about except that it came off a jacuzzi and uses too much power. What about flow rate? Doesn't sound like research to me.

I once met a guy who has kept saltwater tanks for 20+ years but could still not figure out how to keep any corals alive other than mushrooms. Also as an engineer I have to deal with many clients who have issues using some of our products, whenever there's a problem on the clients side the first thing they say is "I've been doing this for so many years, I can't be wrong" but they always are

golf nut · #9 04-14-2009, 04:29 AM

Quote:

Originally Posted by Canuckgod420

Explain your theory on the head pressure please, it would be nice to know for sure.
The way I see it, if I tee off a pump(any pump) the flow coming from either end of the tee would be half of what the flow is straight from the pump...correct?

You did ask this question did you not?

He gave you the correct answer and some free advice, why the hostility?

What is so secret about an OEM pump, I am going to guess that this is an Emerson replacement.

Canuckgod420 · #10 04-14-2009, 04:47 AM

The so called hostility stems from the jerk comment he made at the beginning of the post....I was merely responding to mykas post.

Theres nothing secret about the pump...its just not what the thread was about, and I have no interest in explaining anything more about the pump,and you are incorrect on the emerson replacement? what ever that means.

Never did I say I wasnt grateful for the head pressure calculation. I still have a hard time believing all that when I see how much loss I get from the pumps I run right now....for example....quiet one 4000HH claims 800GPH @ 6'....but on my return to my tank after 6' up and 2 elbows the flow is minimal. I guarantee I am not even getting 400GPH right now.